1. Field of the Invention
The invention relates to respiratory treatment systems, and, in particular, to a system and method of humidifying gas in a respiratory treatment system based on the ambient conditions.
2. Description of the Related Art
Humidifiers are commonly used with ventilators, pressure support systems, and other respiratory devices to add humidity to the gas being supplied to a patient via a patient circuit. The humidity added to the gas supplied to the patient by a conventional ventilator or pressure support system is typically monitored and/or controlled in a feedback loop to provide a consistent humidity level. Typically, the humidity has been monitored by placing a temperature and/or humidity sensor in the ventilator itself, or within the patient circuit to monitor the humidity of the air in the ventilator. An example of such a conventional feedback humidification system is described in published U.S. patent application Ser. No. 09/808,567 (pub. no. 2001/0050080).
Such systems, however, may not provide an appropriate level of humidity to the patient. One reason, discovered by the present inventors, is that conventional feedback humidification system do not take into consideration the condition of the ambient environment in which the patient and ventilator/pressure support system are located.